About transactions and concurrency control

Cassandra does not offer fully ACID-compliant transactions, the standard for transactional
behavior in a relational database systems:

Atomic

Everything in a transaction succeeds or the entire transaction is rolled back.

Consistent

A transaction cannot leave the database in an inconsistent state.

Isolated

Transactions cannot interfere with each other.

Durable

Completed transactions persist in the event of crashes or server failure.

As
a non-relational database, Cassandra does not support joins or foreign keys, and consequently
does not offer consistency in the ACID sense. For example, when moving money from account A to
B the total in the accounts does not change. Cassandra supports atomicity and isolation at the
row-level, but trades transactional isolation and atomicity for high availability and fast
write performance. Cassandra writes are durable.